1. Technical Field
One or more embodiments of the present invention generally relate to scheduling workloads in processors. In particular, embodiments relate to the scheduling of workloads in architectures based on performance indicators.
2. Discussion
Certain modern day computer systems make use of multiple processor packages, where each package plugs into a corresponding socket, has a fully functional processor core, and is often referred to simply as a “processor”. When presented with new tasks to schedule, the conventional approach has been to schedule the tasks on whichever processor is the least busy. Thus, the processor that is being utilized the least, typically receives and executes the instructions associated with the new tasks. As computer system architectures continue to evolve, however, strictly utilization-based scheduling may be unsatisfactory from a performance standpoint as well as a power consumption standpoint.
For example, smaller enclosures, denser transistor arrays and faster processor speeds have led to the use of advanced power saving techniques to conserve power, control temperatures and extend battery life (in the case of mobile platforms). These techniques can involve demand based switching (DBS), which scales the frequency of a processor up or down in order to tradeoff performance for power conservation. Accordingly, it may be increasingly more common for different processors in a system to be operating at different speeds at any given moment. Because operating frequency is often a resource setting that is shared by components other than the processor in question (i.e., resource dependencies may exist), a situation may arise wherein a processor is scaled to a relatively high operating frequency but is not the least utilized processor in the system.
Consider, for example, a dual-core processor with a shared frequency setting, where one of the cores (e.g., “Core1”) is much more utilized than the other core (e.g., “Core2”). In this example, because Core1 is highly utilized, it will be run at a high frequency in order to satisfy the higher demand for the compute workload. Core2 will also be run at the high frequency because the frequency setting is shared by the two cores. Such would be the case even though Core2 has a low demand for the compute workload and ideally should be run at a lower frequency to save or reduce power consumption. In the case of a multi-core, multi-processor system, the result may be one or more low frequency cores running a great number of tasks while at the same time high frequency cores are running few tasks.